Traditional technology allows imposing restrictions on manipulation of printed materials. For example, copying of a printed material may be prohibited according to the importance of printed content.
An example is shown in FIG. 21, where content classified as strictly confidential is printed with a set of symbols * arranged in letters “Strictly Confidential” being superimposed onto text or another print target.
With this method, as mentioned above, the set of symbols * is arranged to read “Strictly Confidential” as an example. The symbols can visually notify users of whether the information contained in the print target of the printed material has so important content as to be classified as strictly confidential.
Further, the method not only visually notifies users of the importance of the content in the print target in the above manner, but also associates the symbols *, etc. with an instructional content for a predetermined control on a print process. As a printer equipped with an image capturing device, such as a scanner, captures the printed, symbol-containing image with the image capturing device, the printer prohibits or otherwise controls a print process for the print target according to the control content associated with the symbols.
In the following part of the specification, these symbols will be called the symbol pattern.
When the printer controls the print process for the printed material in accordance with a symbol pattern (e.g., “*”) provided onto the printed material in this manner, the printer must identify the symbol pattern from the result of image capturing by the image capturing device with high accuracy.
However, results of symbol pattern capturing by the image capturing device can vary depending on the accuracy of image capturing by the image capturing device. The result varies also with irregular printed material results of the symbol pattern due to temporal changes of components of the printer and differences between print processes in individual printers. It is therefore preferable for the image capturing device to be able to capture the symbol pattern with high accuracy even in the presence of irregularities in image capturing accuracy by the image capturing device or irregularities in the printing results of the symbol pattern.
Japanese Unexamined Patent Publication 2002-271625 (Tokukai 2002-271625; published Sep. 20, 2002) discloses an image processing device which adjusts print density to correct irregularities in image capturing between individual devices. However, Tokukai 2002-271625 does not modify data (print-purpose symbol pattern data) to print a symbol pattern in order to identify the symbol pattern with sufficient accuracy.
Conventional technology outputs different results of symbol pattern capturing, depending on print quality of the symbol pattern and accuracy of the image capturing device in the capturing of the symbol pattern. This could result in poor accuracy of the identification of the symbol pattern after capturing the image.
Accordingly, there is a need to capture the symbol pattern with high accuracy even in the presence of irregularities in image capturing accuracy by the image capturing device or irregularities in the printing results of the symbol pattern.